Dentifrice compositions having improved anticalculus properties

ABSTRACT

A storage stable oral composition which is effective against calculus which contains an orally acceptable vehicle having incorporated therein an effective anticalculus combination of about 0.5 to about 2% by weight of a water soluble pyrophosphate salt and about 0.5 to about 3% by weight of a water soluble polyphosphate salt. The presence in the composition of polyvalent metal compounds and fluoride compounds do not affect the stability of the composition as well as reactive ingredients such as peroxide and bicarbonate compounds.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to a dentifrice composition and moreparticularly to a dentifrice composition which contains reactiveingredients and exhibits improved anticalculus properties.

2. The Prior Art

It has been found to be very desirable to incorporate peroxide compoundsin dentifrice compositions, the efficacy of peroxide compounds in oralhygiene having long been recognized. Such compounds have been proveneffective in the treatment of gingivitis, periodontitis and in combatingplaque. Additionally, peroxide compounds have been utilized for oralcosmetic purposes such as tooth whitening which results from bleachingand cleansing of tooth surfaces. Examples of the prior art disclosingperoxide containing dentifrices are found in the disclosures of U.S.Pat. No. 4,971,782, U.S. Pat. No. 4,897,258 and U.S. Pat. No. 4,837,008.

Although the presence of peroxide ingredients in the dentifrice providesantiplaque and whitening efficacy, an improvement in the anticalculus(i.e., antitartar) efficacy of the dentifrice is desired by the art.

Included in the wide variety of chemical agents disclosed by the priorart as being effective as anticalculus agents are the water solublepolyphosphate and pyrophosphate salts. For example, U.S. Pat. No.4,923,684 and U.S. Pat. No. 4,985,236 disclose the use of awater-soluble alkali metal tripolyphosphate as an anticalculus agent indentifrice compositions. The patent discloses that to be storage stable,the tripolyphosphate salt must be incorporated in the dentifrice at aconcentration of at least 4% by weight, the dentifrice having analkaline pH, for example, a pH of 8-10. At concentrations less than 4%by weight, for example, 3% by weight, the patent teaches that thepolyphosphate salt is unstable in the stored dentifrice composition.

U.S. Pat. No. 4,684,518 discloses that water soluble alkali metalpyrophosphate salts are effective as anticalculus agents when present indentifrice compositions at a concentration sufficient to provide atleast 1.5% P₂ O₇ ⁻⁴ anion.

U.S. Pat. No. 5,176,900 discloses a dentifrice composition containing ananticalculus combination of a water soluble tripolyphosphate saltsufficient to provide 0.5-7.5% P₃ O₁₀ anion and a water solubleorthophosphate salt sufficient to provide from 0.2-5% orthophosphateanion, the combination being storage stable at a pH below 8.0.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a storagestable oral composition which is effective against calculus whichcontains an orally acceptable vehicle having incorporated therein aneffective anticalculus combination of about 0.5 to about 2% by weight ofa water soluble pyrophosphate salt and about 0.5 to about 3% by weightof a water soluble polyphosphate salt.

As will hereinafter be demonstrated, a dentifrice containing acombination of water soluble pyrophosphate and polyphosphate salts atthe concentrations indicated above exhibit an anticalculus efficacy atleast equivalent to that exhibited by presently available commercialdentifrice products delivering an anticalculus benefit.

In addition to the anticalculus efficacy, it has also been unexpectedlydiscovered that when the amount of water present in the dentifricecomposition is maintained at a concentration of less than about 9% byweight and preferably about 5 to about 8% by weight, the freepyrophosphate ion concentration as well as any free fluoride ionconcentration incorporated in the dentifrice is maintained atsubstantially the original levels of incorporation in the dentifriceduring storage, in spite of the presence in the dentifrice of reactiveingredients such as peroxide and bicarbonate compounds as well aspolyvalent metal cations, such as calcium ion, which is normallyincompatible with water soluble fluoride and pyrophosphate salts asthese polyvalent cations normally interact to form water insoluble saltswhich are inactive in the aqueous environment of the oral cavity.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The vehicle used to prepare the dentifrice composition of the presentinvention may be substantially anhydrous or contain limited amounts ofwater as well as a suitable humectant such as glycerin, sorbitol,polyethylene glycol, or any suitable mixture thereof. Limited amounts ofwater may be included in the vehicle of the dentifrice composition andpreferably at a concentration of no more than about 9% by weight of thecomposition and most preferably about 5 to about 8% by weight. Whenwater is present in the dentifrice composition in an amount in excess ofabout 9% by weight, the stability of the dentifrice composition isadversely affected.

The proportion of vehicle used to prepare the dentifrice composition ofthe present invention is generally within the range of about 40 to about70% by weight of the dentifrice composition of this invention andpreferably about 50 to about 65% by weight of the dentifricecomposition. Glycerin is present in the dentifrice vehicle of thepresent invention at a concentration of about 10 to about 60% by weightand preferably about 15 to about 40% by weight.

A surfactant is used in the preparation of dentifrice composition of thepresent invention to aid in the thorough dispersion of the dentifricecomposition throughout the oral cavity when applied thereto as well asto improve the cosmetic acceptability and detersive and foamingproperties of the dentifrice. Among the organic surfactants useful inthe practice of the present invention are salts of the higher alkylsulfates, such as sodium lauryl sulfate (SLS) or other suitable alkylsulfate having 8 to 18 carbon atoms in the alkyl group; sodium laurylsulfoacetate, salts of sulfonated monoglycerides of higher fatty acids,such as sodium coconut monoglyceride sulfonate or other suitablesulfonated monoglycerides of a fatty acids of 10 to 18 carbon atoms;salts of amides of higher fatty acid, e.g., 12 to 16 carbon atom acids,with lower aliphatic amino acids, such as sodium-N-methyl-N-palmitoyltauride, sodium N-lauroyl-, N-myristoyl- and N-palmitoyl sarcosinates;salts of the esters of such fatty acids with isothionic acid or withglycerol monosulfate, such as the sodium salt of monosulfatedmonoglyceride of hydrogenated coconut oil fatty acids; salts of olefinsulfonates, e.g. alkene sulfonates or hydroxalkene sulfonates ormixtures thereof having 12 to 16 carbon atoms in the carbon chain of themolecule; and soaps of higher fatty acids, such as those of 12 to 18carbon atoms, e.g., coconut fatty acids. The cation of the salt may besodium potassium or mono-, di or triethanol amine.

The surfactant is included in the dentifrice vehicle of the presentinvention at a concentration of about 0.5 to about 3.0% by weight andpreferably about 1.0 to about 2.0% by weight.

Polishing agents are incorporated in dentifrice composition of thepresent invention and preferred polishing agents are siliceousmaterials, such as silica, and will normally have a mean particle sizeup to about 10 microns and a very high surface area, e.g. in the rangeof 150-750 square meters/gram. A preferred silica is a precipitatedamorphous hydrated silica, such as Sorbosil AC-35 marketed by CrosfieldChemicals, or Zeodent 115 from J. M. Huber Company but other polishingagents may also be employed, including sodium bicarbonate, calciumcarbonate, sodium metaphosphate, potassium metaphosphate, tricalciumphosphate, calcium phosphate dihydrate, anhydrous dicalcium phosphate,calcium pyrophosphate, magnesium orthophosphate, trimagnesium phosphate,alumina trihydrate, aluminum silicate, zirconium silicate, calcinedalumina and bentonite.

The polishing agent is present in the dentifrice composition of thepresent invention at a concentration of about 10 to about 30% by weightand preferably about 5 to about 25% by weight.

Bicarbonate compounds, when included the dentifrice of the presentinvention, are included at a concentration of about 5 to about 20% byweight and preferably about 8 to about 15% by weight. When used at theseconcentrations the pH of the dentifrice is generally in the range ofabout 8 to about 10. The particle size of the bicarbonate compound canrange from about 10 to about 300 microns although a particle size of20-60 microns is preferred, the smaller particle size bicarbonate beingmore readily dispersed in the anhydrous vehicle.

Inorganic thickeners may be included in the dentifrices of the presentinvention and include fumed silicas such as Cab-o-sil available fromCabot Corporation, and thickening silicas including those available fromW. R. Grace designated Sylox 15.

Organic thickeners such as natural and synthetic gums and colloids mayalso be incorporated in the dentifrice composition of the presentinvention, particularly when water in amounts up to about 9% by weightare present in the dentifrice component. Examples of such thickenersinclude carrageenan (Irish moss), xanthan gum and sodium carboxymethylcellulose, starch, polyvinylpyrrolidone, hydroxyethylpropylcellulose,hydroxybutyl methyl cellulose, hydroxypropyl methyl cellulose, andhydroxyethyl cellulose.

The inorganic or organic thickener may be incorporated in thecompositions of the present invention at a concentration of about 0.05to about 2% by weight and preferably about 0.1 to about 1.5% by weight.

Peroxide compounds may be used as an ingredient in the dentifricecomposition of the present invention and when added to the dentifricecomposition are present in the dentifrice at a concentration of about0.25 to about 5% by weight and preferably about 0.5 to about 2.0% byweight. Peroxide compounds suitable for use in the practice of thepresent invention include metal peroxides such as calcium peroxide,magnesium peroxide and zinc peroxide.

Fluoride-providing salts having anti-caries efficacy may also beincorporated in the dentifrice of the present invention and arecharacterized by their ability to release fluoride ions in water. It ispreferable to employ a water-soluble salt fluoride providing about10-2,000 ppm of fluoride ion, and preferably about 1000-1500 ppm offluoride ion. Among these materials are water-soluble inorganic metalsalts, for example, sodium fluoride, potassium fluoride, sodiummonofluorophosphate, and sodium fluorosilicate. Sodium fluoride andsodium monofluorophosphate are preferred fluoride-providing salts.

Pyrophosphate salts having anticalculus efficacy useful in the practiceof the present invention include water soluble salts such as dialkali ortetra-alkali metal pyrophosphate salts such as Na₄ P₂ O₇ (TSPP), K₄ P₂O₇, Na₂ K₂ P₂ O₇, Na₂ H₂ P₂ O₇ and K₂ H₂ P₂ O₇. Polyphosphate saltsinclude the water soluble alkali metal tripolyphosphates such as sodiumtripolyphosphate (STPP) and potassium tripolyphosphate.

The pyrophosphate salts are incorporated in the dentifrice compositionof the present invention at a concentration of about 0.5 to about 2.0%by weight, and preferably about 1.5 to about 2% by weight and thepolyphosphate salts are incorporated in the dentifrice composition ofthe present invention at a concentration of about 1.0 to about 3.0% byweight and preferably about 2 to about 3% by weight.

Colorants such as pigments and dyes may be used in the practice of thepresent invention. Pigments include non-toxic, water insoluble inorganicpigments such as titanium dioxide and chromium oxide greens, ultramarineblues and pinks and ferric oxides as well as water insoluble dye lakesprepared by extending calcium or aluminum salts of FD&C dyes on aluminasuch as FD&C Green #1 lake, FD&C Blue #2 lake, FD&C R&D #30 lake andFD&C # Yellow 15 lake. The pigments have a particle size in the range of5-1000 microns, preferably 250-500 microns, and are present at aconcentration of 0.5 to 3% by weight.

Dyes used in the practice of the present invention are generally foodcolor additives presently certified under the Food Drug & Cosmetic Actfor use in food and ingested drugs, including dyes such as FD&C Red No.3 (sodium salt of tetraiodofluorescein), FD&C Yellow No. 5 (sodium saltof 4-p-sulfophenylazo-1-p-sulfophenyl-5-hydroxypyrazole-3 carboxylicacid), FD&C Yellow No. 6 (sodium salt ofp-sulfophenylazo-B-naphtol-6-monosulfonate), FD&C Green No. 3 (disodiumsalt of4-{[4-(N-ethyl-p-sulfobenzylamino)-phenyl]-(4-hydroxy-2-sulfoniumphenyl)-methylene}-[1-(N-ethyl-N-p-sulfobenzyl)-Δ-3,5-cyclohexadienimine],FD&C Blue No. 1 (disodium salt ofdibenzyldiethyldiaminotriphenylcarbinol trisulfonic acid anhydrite),FD&C Blue No. 2 (sodium salt of disulfonic acid of indigotin) andmixtures thereof in various proportions. The concentration of the dyefor the most effective result in the present invention is present in thedentifrice composition in an amount from about 0.0005 percent to about 2percent of the total weight.

Any suitable flavoring or sweetening material may also be incorporatedin the dentifrice composition of the present invention. Examples ofsuitable flavoring constituents are flavoring oils, e.g., oils ofspearmint, peppermint, wintergreen, sassafras, clove, sage, eucalyptus,marjoram, cinnamon, lemon, and orange, and methyl salicylate. Suitablesweetening agents include sucrose, lactose, maltose, sorbitol, xylitol,sodium cyclamate, perillartine, and sodium saccharin. Suitably, flavorand sweetening agents may together comprise from 0.01% to 5% or more ofthe preparations.

Various other materials may be incorporated into the dentifricecomposition of this invention. Non-limiting examples thereof includepreservatives, silicones and chlorophyll compounds, antibacterial agentssuch as chlorohexidene, halogenated diphenyl ethers such as Triclosan,desensitizing agents such as potassium nitrate and potassium citrate andmixtures thereof. These adjuvants are incorporated in the dentifricecomponents in amounts which do not substantially adversely affect theproperties and characteristics desired, and are selected and used inproper amounts, depending upon the particular type of dentifricecomponent involved.

To prepare the dentifrice composition of the present invention, thehumectants e.g. glycerin and glycol humectants and sweetener aredispersed in a conventional mixer until the mixture becomes ahomogeneous gel phase. Into the gel phase are added a colorant, theanticalculus agents and a fluoride anticaries agent. These ingredientsare mixed until a homogeneous phase is obtained. Thereafter thethickener, polishing agent, reactive ingredient such as peroxide,bicarbonate salts, flavor and surfactant ingredients are added and theingredients mixed at high speed under vacuum of about 20-100 mm Hg. Theresultant product is a homogeneous, semi-solid, extrudable pasteproduct.

The following examples illustrate this invention further. Allproportions and amounts therein and elsewhere in this specification areby weight unless otherwise indicated.

EXAMPLE I

To demonstrate the anticalculus efficacy of the composition of thepresent invention, a dentifrice composition of the present inventiondesignated "Composition A" was prepared containing 2% TSPP and 3% STPPfollowing the procedure previously described containing the ingredientslisted in Table I below.

                  TABLE 1                                                         ______________________________________                                        Composition A                                                                 Ingredients                                                                   ______________________________________                                        Glycerin            25.00%                                                    PEG 600             3.00                                                      Propylene Glycol    17.94                                                     Na Saccharin        0.50                                                      Xanthan             0.20                                                      Carboxymethyl Cellulose                                                                           0.20                                                      MFP                 0.76                                                      TSPP                2.00*                                                     STPP                3.00                                                      TiO.sub.2           0.50                                                      Zeodent 115         21.00                                                     F D & C Green #3 Dye                                                                              0.20                                                      (1%) Soln.                                                                    Sylox 15            2.50                                                      NaHCO.sub.3         12.00                                                     CaO.sub.2           0.50                                                      Flavor              1.0                                                       SLS                 1.70                                                      Water               6.00                                                      Na.sub.2 CO.sub.3   2.00                                                      ______________________________________                                         *2% TSPP provides 1.3% P.sub.2 O.sub.7.sup.-4 ion                        

To determine whether the presence of the combination of TSPP and STPP atthe concentration levels present in Composition A (2% TSPP and 3% STPP)would provide acceptable anticalculus efficacy, in vitro testing ofComposition A was conducted in accordance with the following procedure:

Composition A was diluted with water and centrifuged to obtain asupernatant which was diluted 20× with water and hydroxy apatite seeds(68 m² /g) were then suspended in the diluted supernatant overnight at37° C. The treated seeds were then separated from the supernatant andadded to a crystal growth solution containing 1.06 mm CaCl₂ and 0.63 mMKH₂ PO₄ and 150 mM NaCl.

The pH of the growth solution was recorded as a function of time, a pHdrop being an indication of potential HAP crystal (i.e. tartar) growth.

The results of the in vitro test are recorded in Table II below. Forpurposes of comparison, the test was repeated except the dentifricestested included a commercially available anticalculus toothpastedesignated "Commercial Toothpaste I" and a second commercial toothpastewhich did not claim an anticalculus benefit designated "CommercialToothpaste II" sold by different manufacturers as well as a controldentifrice identical in composition to Composition A except that TSPPand STPP were not included in the composition, was also tested.

The results obtained with the commercial and control toothpastes arealso recorded in Table II below.

                  TABLE II                                                        ______________________________________                                                       pH                                                             Dentifrice       0 min.    15 min. 30 min.                                    ______________________________________                                        Composition A    7.38      7.25    7.22                                       Commercial Toothpaste I                                                                        7.37      7.07    7.04                                       Commercial Toothpaste II                                                                       7.38      6.48    6.40                                       Control          7.38      6.88    6.81                                       ______________________________________                                    

The results recorded in Table II indicate that Composition A sustained apH drop of a magnitude less than the pH drop sustained by theanticalculus Commercial Toothpastes or the Control dentifrice indicatingthat Composition A would provide an anticalculus efficacy greater thanthe Commercial Toothpastes.

EXAMPLE II

Composition B having the composition listed in the Table III below wereprepared following the procedure of Example I. Dentifrices B was thenloaded into a plastic laminated tube, sealed and then aged at 105° F.for 2 months. The plastic laminated tube contents were analyzed afterthe aging period. The analysis results are summarized in Table IV below.

                  TABLE III                                                       ______________________________________                                        Composition B                                                                 Ingredient           wt. %                                                    ______________________________________                                        Glycerin             25.2486                                                  Zeodent 115          21.0000                                                  Propylene Glycol     17.8900                                                  Sodium Bicarbonate   12.0000                                                  Deionized Water      6.0000                                                   Polyethylene Glycol 600                                                                            3.0000                                                   Sodium Tripolyphosphate                                                                            3.0000                                                   Hydrated Amorphous Silica                                                                          2.5000                                                   Na.sub.2 CO.sub.3    2.0000                                                   Tetrasodium Pyrophosphate                                                                          2.0000                                                   Sodium Lauryl Sulfate                                                                              1.7000                                                   Sodium Monofluorophosphate                                                                         0.760                                                    Flavor               1.00                                                     Sodium Saccharin     0.5000                                                   Titanium Dioxide     0.5000                                                   Calcium Peroxide     0.5000                                                   Xanthan Gum          0.2000                                                   Sodium Carboxymethyl Cellulose                                                                     0.2000                                                   F D & C Green #3 Dye 0.0014                                                   TOTAL                100.0000                                                 ______________________________________                                    

                  TABLE IV                                                        ______________________________________                                        Aging of Composition B at 105° F.                                      Initial          2 Months                                                                    %                       %                                      %      %       Soluble   %      %      Soluble                                TSPP   STPP    Fluoride  TSPP   STPP   Fluoride                               ______________________________________                                        1.8    3.1     0.096     2.0    2.7    0.097                                  ______________________________________                                    

The results recorded in Table IV indicate that Composition B issubstantially storage stable with little or no change in theconcentration of TSPP, STPP or soluble fluoride ingredients.

What is claimed is:
 1. An aqueous fluoride gel or paste which is storagestable and is effective against calculus, the dentifrice comprising avehicle containing about 5 to about 9% by weight water, havingincorporated therein a water soluble fluoride compound providing about10 to 2,000 ppm fluoride ion and a combination of about 0.5 to no morethan about 3% by weight of a water soluble alkali metal polyphosphateand about 0.5 to no more than about 2.0% by weight of a water solublealkali metal pyrophosphate which composition is stable and effective toreduce calculus formation on teeth in the oral cavity.
 2. The dentifricecomposition of claim 1 wherein the water soluble alkali polyphosphate issodium tripolyphosphate.
 3. The dentifrice composition of claim 1wherein the alkali metal pyrophosphate is sodium pyrophosphate.
 4. Thedentifrice composition of claim 1 wherein a polyvalent metal compound isincorporated in the vehicle.
 5. The dentifrice composition of claim 4wherein the polyvalent metal compound is a polyvalent metal peroxide. 6.The dentifrice composition of claim 5 wherein the polyvalent metalperoxide is calcium peroxide.
 7. The dentifrice composition of claim 1wherein a bicarbonate compound is incorporated in the vehicle.
 8. Thedentifrice composition of claim 7 wherein the bicarbonate compound issodium bicarbonate.
 9. The dentifrice composition of claim 1 wherein thefluoride compound is sodium monofluorophosphate.
 10. The dentifricecomposition of claim 1 wherein there is incorporated in the vehicle apolyvalent compound, a peroxide compound, a bicarbonate compound and afluoride compound.
 11. A method for reducing calculus of thosesusceptible of forming calculus and for treating diseases of the oralcavity by applying to teeth in the cavity an aqueous fluoride gel orpaste comprising a vehicle containing about 5 to about 9% by weightwater having incorporated therein a water soluble fluoride compoundproviding about 10 to 2000 ppm fluoride ion and a combination of about0.5 to no more than about 2% by weight of a water soluble alkali metalpyrophosphate and about 0.5 to no more than about 3% by weight of watersoluble alkali metal polyphosphate.
 12. The method of claim 11 whereinthe water soluble alkali polyphosphate is sodium tripolyphosphate. 13.The method of claim 11 wherein the alkali metal pyrophosphate is sodiumpyrophosphate.
 14. The method of claim 11 wherein a polyvalent metalcompound is incorporated in the vehicle.
 15. The method of claim 14wherein the polyvalent metal compound is a polyvalent metal peroxide.16. The method of claim 15 wherein the polyvalent metal peroxide iscalcium peroxide.
 17. The method of claim 11 wherein a bicarbonatecompound is incorporated in the vehicle.
 18. The method of claim 17wherein the bicarbonate compound is sodium bicarbonate.
 19. The methodof claim 11 wherein the fluoride compound is sodium monofluorophosphate.20. The method of claim 11 wherein there is incorporated in the vehiclea polyvalent metal compound, a peroxide compound, a bicarbonate compoundand a fluoride compound.
 21. A dentifrice composition which is storagestable and is effective against calculus, the dentifrice comprising anaqueous gel or paste vehicle having incorporated therein (A) sodiumbicarbonate (B) about 0.25 to about 5% by weight of a calcium, magnesiumor zinc metal peroxide and mixtures thereof (C) about 0.5 to no morethan about 2.0% by weight of sodium or potassium pyrophosphate andmixtures thereof (D) about 0.5 to no more than about 3% by weight ofsodium or potassium polyphosphate and mixtures thereof (E) sodium orpotassium fluoride or monofluorophosphate and mixtures thereof, and (F)water, maintained at a concentration of from about 5% to less than about9% by weight, the combination being effective to reduce the formation ofcalculus on teeth in the oral cavity.